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| Oceanic plateaus | |
|---|---|
| Name | Oceanic plateaus |
| Type | Igneous province |
| Location | Global oceans |
| Area | Variable |
| Formed | Mesozoic–Cenozoic |
| Composition | Basaltic to rhyolitic |
| Parent | Large igneous provinces |
Oceanic plateaus are large, relatively flat submarine regions of thickened crust formed mainly by massive volcanic eruptions and intrusions. They stand out from surrounding abyssal plains by elevated topography and atypical crustal thickness produced during episodes linked to mantle processes, plume activity, and plate reorganizations. Oceanic plateaus influence ocean circulation, biogeography, and continental breakup, and many are key markers in the geological records of Cretaceous magmatism, Paleogene events, and plate tectonic reconstructions involving plates such as the Pacific Plate, Nazca Plate, Atlantic Ocean plates, and the Indian Plate.
Oceanic plateaus are defined as extensive submarine igneous provinces distinguished by crustal thickness often exceeding typical oceanic crust values and by areal extents comparable to continental regions; they are classed among Large igneous provinces and are characterized by high-volume flood basalt emplacement. Typical plateaus display elevated topography above surrounding abyssal plain bathymetry, commonly host thick sedimentary covers, and exhibit seismic signatures of underplated mafic complexes and intrusive sills similar to those beneath Iceland and the Deccan Traps. Their identification relies on integrated studies by institutions including the United States Geological Survey, British Geological Survey, Institut de Physique du Globe de Paris, and research vessels from organizations like the National Oceanic and Atmospheric Administration and Woods Hole Oceanographic Institution.
Oceanic plateau formation is linked to transient mantle phenomena such as mantle plumes from the African superswell or the Hawaii hotspot system, combined with lithospheric extension related to events like the breakup of Pangaea and the rifting of microcontinents such as India from Madagascar. Episodes such as the emplacement of the Ontong Java Plateau during the Early Cretaceous coincide with global environmental perturbations recorded at boundaries like the Cretaceous–Paleogene boundary and the Valanginian event. Geochemical fingerprints include isotope systematics from laboratories associated with Scripps Institution of Oceanography and the University of Cambridge that trace sources to enriched mantle components and recycled crustal materials similar to signatures from the Kerguelen Plateau and the Shatsky Rise.
The composition of oceanic plateaus spans tholeiitic basalts, evolved andesites, and intrusive gabbros with localized rhyolitic suites documented on plateaus such as Iceland-adjacent provinces and the Ontong Java Plateau. Seismic reflection and refraction profiles by groups at the Lamont–Doherty Earth Observatory reveal layered crustal architecture including extrusive basalt flows, sheeted sills, and underplated magma bodies comparable to structures beneath the Columbia River Basalt Group on continents. Mineral assemblages and trace element ratios analyzed at institutions like the Geological Survey of Japan indicate fractionation and crustal assimilation processes analogous to those implicated in the development of the Kurile–Kamchatka Arc and the Aleutian Arc.
Tectonic evolution of oceanic plateaus involves emplacement on divergent, convergent, or intraplate settings and subsequent modification by plate interactions such as subduction below arcs like the Mariana Islands, accretion to continental margins as in parts of the North American Cordillera, or fragmentation during seafloor spreading episodes that created features adjacent to the Mid-Atlantic Ridge and the Carlsberg Ridge. Plateaus can act as subducting aseismic ridges that alter slab geometry and lead to events recorded in tectonic reconstructions by the Paleomagnetic Research Group at institutions like the Geological Survey of Canada. Their longevity is shaped by processes observed in the evolution of the Agulhas Plateau, the Kerguelen Plateau, and the Greater Ontong Java complex.
Oceanic plateaus exert strong controls on pelagic and benthic ecosystems by creating bathymetric highs that modify currents such as the Gulf Stream, the Antarctic Circumpolar Current, and the Equatorial Undercurrent, enhancing productivity and facilitating biogeographic isolation comparable to the role of seamount chains like the Emperor Seamounts. Plateaus host coral communities, chemosynthetic faunas near magmatic sulfide occurrences, and fisheries exploited by fleets regulated under organizations like the United Nations conventions and regional bodies including the North Pacific Fishery Management Council and the Commission for the Conservation of Antarctic Marine Living Resources. Paleontological records from plateaus contribute to large-scale extinction and recovery studies tied to events curated by museums such as the Smithsonian Institution and the Natural History Museum, London.
Oceanic plateaus are associated with mineral resources including massive sulfides, ferromanganese crusts, and potential hydrocarbon reservoirs in sedimented basins attracted the attention of companies like BP and ExxonMobil and nations such as Japan, India, and China pursuing seabed minerals. Plateaus influence tsunami generation and seismicity when interacting with subduction zones, producing hazards documented in events investigated by the International Seismological Centre, the Pacific Tsunami Warning Center, and case studies such as the 2011 Tōhoku earthquake and tsunami. Geohazards also include slope failure and mass wasting episodes recorded by surveys from the Canadian Hydrographic Service and the GEOMAR Helmholtz Centre for Ocean Research Kiel.
Notable oceanic plateaus include the Ontong Java Plateau, the Kerguelen Plateau, the Agulhas Plateau, the Shatsky Rise, and the Farallon Plate remnants preserved along continental margins; other significant features are the Manihiki Plateau, the Carlsberg Ridge-adjacent plateaus, and the Lord Howe Rise. These are distributed across the Pacific Ocean, the Indian Ocean, and the South Atlantic Ocean, and their study involves collaborations among institutions like the International Ocean Discovery Program, the International Association of Volcanology and Chemistry of the Earth's Interior, and national programs in Australia, New Zealand, South Africa, and Chile.
Category:Large igneous provinces